A sealing mat for sealing the open mouths of an array of test tubes. The mat includes a flexible carrier sheet having an array of mutually spaced pegs projecting downwardly therefrom and a plurality of plugs. The plugs are externally configured and dimensioned to be inserted in and to seal the open mouths of the test tubes. Each of the plugs has an upwardly facing recess internally configured and dimensioned to receive and coact in frictional engagement with a respective one of the pegs to thereby releasably secure the plugs to the carrier sheet. The carrier sheet is separable from the thus inserted plugs by flexure to extract the pegs from the recesses.